Observations on the ability of avian reovirus vaccination of hens to protect their progeny against the effects of challenge with homologous and heterologous strains.

Avian reovirus vaccines of the S1133 strain, used indirectly in the dams of challenged chicks, were found to confer protection against clinical signs and/or deaths resulting from the use of both homologous and heterologous challenge strains. There was some protection against every strain used, although this did vary in degree. It was difficult to relate this variation in protection to the differences in in vitro neutralization of the strains by S1133 antiserum, though there were some similarities.